In such fields as road milling, mining and trenching, superhard materials, such as polycrystalline diamond, may be used to breakup tough materials such as asphalt, concrete and rock. High-pressure high-temperature (“HPHT”) presses are commonly employed to create such superhard materials. While HPHT presses have been made in a variety of styles over the years, many HPHT presses comprise a plurality of piston assemblies that may act in concert to pressurize a cell. One example of such an HPHT press is disclosed in U.S. Pat. No. 6,336,802 to Hall which describes a press with a frame comprising intersecting boreholes with means for attachment of a plurality of cartridges. Each cartridge may comprise a piston therein with an anvil protruding there from into a cavity resulting from an intersection of the boreholes. Advancement of the anvils toward a center of the cavity may enclose and define a high-pressure chamber within the press.
A cell may be disposed within such a high-pressure chamber comprising the raw components required to form superhard materials. One example of raw components capable of forming a superhard material comprises diamond grains disposed within a metal canister adjacent a carbide substrate. The carbide substrate may comprise a catalyst that may sweep into the diamond grains under certain HPHT conditions to aid in sintering the diamond grains together. One or more such canisters may be surrounded by a pressure-transferring medium, such as pyrophyllite, that may form a pressure sealing gasket within gaps between adjacent anvils as well as balance pressure around the canisters. Electrically resistive materials may also be disposed within such cells that may heat the cells to desired temperatures when electricity is passed through the cell from one anvil to another.
One known cell configuration, shown in FIG. 1, comprises a cube 100 generally made of pyrophyllite. The cube 100 comprises a cylindrical bore 105 there though. A plurality of metal canisters 110 may be stacked face-to-face, secured within a salt form 108 disposed within the cylindrical bore 105. A metal tube 109 may surround the salt form 108 and provide an electrical path from one end to another. At least one electrically resistive heater 107 may sit on either end of the salt form 108 and provide heat when electricity is passed there through.
While the cell configuration shown in FIG. 1 may be symmetrical end-to-end, it lacks symmetry in the eight other possible planes of symmetry 202 shown in FIG. 2. Such asymmetry may lead to uneven pressure and/or heat distribution. Specifically, each of the plurality of canisters may experience different pressure and temperature gradients throughout its interior based on its unique position relative to the anvils and resistive heaters. Thus, a need exists for more balanced cell designs than previously existing.